/*
 * Copyright (c) 1999 World Wide Web Consortium
 * (Massachusetts Institute of Technology, Institut National de Recherche
 *  en Informatique et en Automatique, Keio University).
 * All Rights Reserved. http://www.w3.org/Consortium/Legal/
 *
 * The original version of this interface comes from SAX :
 * http://www.megginson.com/SAX/
 *
 * $Id: ErrorHandler.java 477010 2006-11-20 02:54:38Z mrglavas $
 */
package org.w3c.css.sac;


/**
 * Basic interface for CSS error handlers.
 * 
 * <p>
 * If a CSS application needs to implement customized error handling, it must
 * implement this interface and then register an instance with the CSS parser
 * using the parser's setErrorHandler method. The parser will then report all
 * errors and warnings through this interface.
 * </p>
 * 
 * <p>
 * The parser shall use this interface instead of throwing an exception: it is
 * up to the application whether to throw an exception for different types of
 * errors and warnings. Note, however, that there is no requirement that the
 * parser continue to provide useful information after a call to fatalError (in
 * other words, a CSS driver class could catch an exception and report a
 * fatalError).
 * </p>
 * 
 * <p>
 * The HandlerBase class provides a default implementation of this interface,
 * ignoring warnings and recoverable errors and throwing a SAXParseException for
 * fatal errors. An application may extend that class rather than implementing
 * the complete interface itself.
 * </p>
 *
 * @author Philippe Le Hegaret
 * @version $Revision: 477010 $
 */
public interface ErrorHandler {

	/**
	 * Receive notification of a warning.
	 * 
	 * <p>
	 * CSS parsers will use this method to report conditions that are not errors
	 * or fatal errors as defined by the XML 1.0 recommendation. The default
	 * behaviour is to take no action.
	 * </p>
	 * 
	 * <p>
	 * The CSS parser must continue to provide normal parsing events after
	 * invoking this method: it should still be possible for the application to
	 * process the document through to the end.
	 * </p>
	 *
	 * @param exception            The warning information encapsulated in a CSS parse exception.
	 * @see CSSParseException
	 * @exception CSSException                Any CSS exception, possibly wrapping another exception.
	 */
	public void warning(CSSParseException exception) throws CSSException;

	/**
	 * Receive notification of a recoverable error.
	 * 
	 * <p>
	 * This corresponds to the definition of "error" in section 1.2 of the W3C
	 * XML 1.0 Recommendation. For example, a validating parser would use this
	 * callback to report the violation of a validity constraint. The default
	 * behaviour is to take no action.
	 * </p>
	 * 
	 * <p>
	 * The CSS parser must continue to provide normal parsing events after
	 * invoking this method: it should still be possible for the application to
	 * process the document through to the end. If the application cannot do so,
	 * then the parser should report a fatal error even if the XML 1.0
	 * recommendation does not require it to do so.
	 * </p>
	 *
	 * @param exception            The error information encapsulated in a CSS parse exception.
	 * @see CSSParseException
	 * @exception CSSException                Any CSS exception, possibly wrapping another exception.
	 */
	public void error(CSSParseException exception) throws CSSException;

	/**
	 * Receive notification of a non-recoverable error.
	 * 
	 * <p>
	 * This corresponds to the definition of "fatal error" in section 1.2 of the
	 * W3C XML 1.0 Recommendation. For example, a parser would use this callback
	 * to report the violation of a well-formedness constraint.
	 * </p>
	 * 
	 * <p>
	 * The application must assume that the document is unusable after the
	 * parser has invoked this method, and should continue (if at all) only for
	 * the sake of collecting addition error messages: in fact, CSS parsers are
	 * free to stop reporting any other events once this method has been
	 * invoked.
	 * </p>
	 *
	 * @param exception            The error information encapsulated in a CSS parse exception.
	 * @see CSSParseException
	 * @exception CSSException                Any CSS exception, possibly wrapping another exception.
	 */
	public void fatalError(CSSParseException exception) throws CSSException;

}
